Jul 15 – 19, 2024
Perimeter Institute for Theoretical Physics
America/Toronto timezone
Reminder: Monday and Tuesday's sessions take place at Federation Hall (University of Waterloo), with the remainder of the week at Perimeter Institute.

Against Horndeski

Jul 18, 2024, 11:45 AM
PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)

PI/1-100 - Theatre

Perimeter Institute for Theoretical Physics



Cliff Burgess


The Horndeski program is motivated by arguing that scalar-tensor modifications to gravity should have two properties: effective interactions that are at most second-order in time derivatives and only a single scalar. I will argue against both of these criteria. First I argue why the low-energy limit of known well-behaved theories can have more than two-derivative field equations. Second I argue why the scalar-tensor interactions most likely to be found competing with gravity at very low energies typically are those with two derivatives, at least when semiclassical methods are justified, and this suggests exploring multiple-scalar models.

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